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  • Open Access

    ABSTRACT

    On the efficiency of generic BE substructuring algorithms based on Krylov solvers

    F.C. Araújo1, L.J. Gray2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.2, pp. 41-46, 2007, DOI:10.3970/icces.2007.002.041

    Abstract This paper is concerned with the solution of boundary-element models based on substructuring. Structured matrix-vector products and the matrix-copy option are proposed to increase the efficiency of algorithms based on Krylov solvers. The former technique was designed to avoid the excessive number of conditional tests during solver iterations, and the latter one, to avoid the repeated calculation of coefficient matrices for identical subregions. Potential applications of the algorithm to composite materials, and to develop parallel codes, are noted. More >

  • Open Access

    ABSTRACT

    Probabilistic Neural Network for Predicting the Stability numbers of Breakwater Armor Blocks

    Doo Kie Kim1, Dong Hyawn Kim2, Seong Kyu Chang1, Sang Kil Chang1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.2, pp. 35-40, 2007, DOI:10.3970/icces.2007.002.035

    Abstract The stability numbers determining the Armor units are very important to design breakwaters, because armor units are designed for defending breakwaters from repeated wave loads. This study presents a probabilistic neural network (PNN) for predicting the stability number of armor blocks of breakwaters. PNN used the experimental data of van der Meer as train and test data. The estimated results of PNN were compared with those of empirical formula and previous artificial neural network (ANN) model. The comparison results showed the efficiency of the proposed method in the prediction of the stability numbers in spite of data incompleteness and incoherence.… More >

  • Open Access

    ABSTRACT

    Advanced Probabilistic Neural Network for the Prediction of Concrete Strength

    Doo Kie Kim1, Seong Kyu Chang1, Sang Kil Chang1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.1, pp. 29-34, 2007, DOI:10.3970/icces.2007.002.029

    Abstract Accurate and realistic strength estimation before the placement of concrete is highly desirable. In this study, the advanced probabilistic neural network (APNN) was proposed to reflect the global probability density function by summing the heterogeneous local probability density function automatically determined in the individual standard deviation of variables. Currently, the estimation of the compressive strength of concrete is performed by a probabilistic neural network (PNN) on the basis of concrete mix proportions, and the PNN is improved by the iteration method. However, an empirical method has been incorporated to specify the smoothing parameter in the PNN technique, causing significant uncertainty… More >

  • Open Access

    ABSTRACT

    Partitioned Formulation for Solving 3D Frictional Contact Problems with BEM using Localized Lagrange Multipliers

    L. Rodríguez-Tembleque1, J.A. González1, R. Abascal1, K.C. Park2, C.A. Felippa2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.1, pp. 21-28, 2007, DOI:10.3970/icces.2007.002.021

    Abstract This work presents an interface treatment method based on localized Lagrange Multipliers (LLM) to solve frictional contact problems between two 3D elastic bodies. The connection between the solids is done using a displacement frame intercalated between the interfaces meshes, and the LLM are collocated at the interface nodes. The Boundary Elements Method (BEM) is used to compute the influence coefficients of the surface points involved, and contact conditions are imposed using projection functions. The LLM provides a partitioned formulation which preserves software modularity, facilitates non-matching meshes treatment and passes the contact patch test [4]. More >

  • Open Access

    ABSTRACT

    Topology optimization of structures with local and global stress constraints

    J. París1, M. Casteleiro1, F. Navarrina1, I. Colominas1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.1, pp. 13-20, 2007, DOI:10.3970/icces.2007.002.013

    Abstract Topology structural optimization problems have been usually stated in terms of a maximum stiffness (minimum compliance) approach. In this kind of formulations, the aim is to distribute a given amount of material in a certain domain, so that the stiffness of the resulting structure is maximized for a given load case. In addition, no stress or displacement constraints are taken into account. This paper presents a different strategy: a minimum weight Finite Element formulation for optimization of continuum structures subjected to stress constraints. We propose two different approaches to take into account the stress constraints in the optimization formulation. The… More >

  • Open Access

    ABSTRACT

    Thermal-Mechanical Buckling Analysis of Laminated Composite Shells by Finite Element Method

    J. Li1, Z.H. Xiang1, M.D. Xue1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.1, pp. 7-12, 2007, DOI:10.3970/icces.2007.002.007

    Abstract This paper presents a finite element scheme to analyze the buckling behavior of composite shells subjected to thermal and mechanical loads. Firstly, a kind of multi-layered composite shell element with relative degrees-of-freedom is adopted to model laminated composite shells. Then the corresponding temperature element is developed so that the mechanical analysis and the thermal analysis share a common mesh. Moreover, a new criterion of critical heat flux is proposed in stead of the traditional criterion of critical temperature. Finally, the advantage of the proposed scheme is illustrated by calculating the stable region of thermal-mechanical loads for a honeycomb sandwich composite… More >

  • Open Access

    ABSTRACT

    Simple Common Plane Contact Detection Algorithm For Fe/Fd Methods

    Oleg Vorobiev1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.1, pp. 1-6, 2007, DOI:10.3970/icces.2007.002.001

    Abstract Common-plane (CP) algorithm is widely used in Discrete Element Method (DEM) to model contact forces between interacting particles or blocks. A new simple contact detection algorithm is proposed to model contacts in FE/FD methods which is similar to the CP algorithm. The CP is defined as a plane separating interacting faces of FE/FD mesh instead of blocks or particles in the original CP method. The method does not require iterations. It is very robust and easy to implement both in 2D and 3D case. More >

  • Open Access

    ABSTRACT

    Bridge Health Mornitoring using Wireless Sensor Networks

    Byung-wan Jo1, Do-keun Kim2, Sung-keun Song3, Suk-un Kim4

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.4, pp. 167-172, 2007, DOI:10.3970/icces.2007.001.167

    Abstract Wireless sensor networks bring new challenges to Bridge monitoring. To monitor a bridge, behavior, including vibration and displacement, must be measured to analyze the health of the structure based on measured and collected data. The collected data can be used to compute modal properties of the bridge. A bridge is moved by external forces, including wind, seismic activity, and traffic. So it is very hard reliance of safety through a preexistence method which uses Data Logger. Dynamic behavior of a bridge is difficult to measure because of costs and installation methods. In this paper, a new method, using a U-Smart… More >

  • Open Access

    ABSTRACT

    Crack Closure Effects in Selected Cases with Practical Engineering Impacts

    I. Cerný 1, V. Linhart1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.4, pp. 161-166, 2007, DOI:10.3970/icces.2007.001.161

    Abstract Two different cases with the aim to show, how important the crack closure phenomenon can be in reality and can affect eventual crack growth behaviour by an unexpected way are described and discussed in the paper, namely: (i) a favourable effect of fretting oxidation crack closure in air which can disappear in oil environments, typical for many machinery applications and (ii) a favourable effect of crack closure occurring as a results of corrosion products in corrosive environments, which would normally increase crack growth rate by stress corrosion and corrosion fatigue mechanisms. More >

  • Open Access

    ABSTRACT

    Reconstruction and Evaluation of 3D Fracture Surface Morphology

    K. Slámečka1, J.Pokluda1, P. Ponížil 2, P. Šandera1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.4, pp. 153-160, 2007, DOI:10.3970/icces.2007.001.153

    Abstract In the paper a procedure for evaluation of the fracture surface morphology is described in detail. It consists of the stereophotogrammetrical 3D surface reconstruction followed by the Delaunay triangulation of obtained set of surface points. The potential of the procedure is demonstrated using fracture surfaces generated under combined bending-torsion fatigue loading of specimens made from high-strength low-alloy Cr-Al-Mo steel. Fracture profiles extracted from calculated 3D meshes are characterized by the root mean square roughness and the Hurst exponent. As a main result of the analysis the critical portion of the torsion loading component after which the character of the crack… More >

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